A new trend is sweeping across South Korea’s youth: personality tests based on the concepts of testosterone and estrogen, labelled as ‘teto’ and ‘egen’, are becoming the latest markers of identity and compatibility, especially among young singles. This hormone-inspired typology is rapidly nudging aside the long-dominant MBTI as the go-to tool for self-understanding, social interaction, and even dating decisions—a phenomenon already echoed by pop culture and social media, and increasingly stirring discussion among experts.
The hormone-based personality test, known widely as the ‘teto-egen’ test, invites users to answer a series of 28 questions. These questions evaluate energy types and interpersonal styles, ultimately classifying participants as either ‘teto’ (testosterone-associated) or ‘egen’ (estrogen-associated). Young people are not just using these terms for self-description, but also to gauge compatibility when forming relationships, a practice that has migrated into everything from blind dating rituals to K-pop fan communities, according to a recent report from The Straits Times (straitstimes.com).
The significance of this trend runs deeper than a simple personality quiz. It highlights a broader social appetite for quick, accessible self-understanding and communication tools amid a backdrop of rapid digitalisation and social change. In South Korea, this shift has found special resonance among the so-called “MZ Generation”—a marketing term referring to Millennials and Generation Z, those born between 1980 and 2005.
By segmenting people into archetypes—teto men are “masculine and athletic”, egen men “gentle and appearance-conscious”, teto women “expressive and extroverted”, and egen women “reserved and traditionally feminine”—the test gives its participants more than just labels. It offers perceived insight into romantic compatibility. As one 30-year-old office worker told the press, “I get emotionally drained easily and tend to be very sensitive in relationships. So I make sure to check their MBTI and whether they’re a ‘teto’ or ‘egen’ type.” Another young participant explained, “I’m an ‘egen woman’, so feminine clothing suits me well. But my personality is more like a ‘teto woman’—I’m bold and outgoing.”
The rapid rise of ‘teto-egen’ typology in South Korea is rooted in online culture. On platforms like Instagram, YouTube Shorts, and webtoons, millions share their test results, speculate about celebrities’ hormone identities, and discuss everything from fashion to workplace behaviour through the test’s lens. Celebrities such as members of Aespa and IU are now routinely categorised by these archetypes in fan discussions. According to figures reported as of 10 July, over 1.16 million people had taken the test on Types, one of the most prominent online personality test platforms in Korea (straitstimes.com).
The momentum picked up dramatically in 2024, aided by pop culture spotlights. A comedy skit in the final episode of Saturday Night Live Korea’s second season on Coupang Play featured a storyline about romantic rivalries determined by teto and egen traits, complete with a “teto transformation” montage that drew sympathy and laughs.
But few trends exist in a vacuum. The roots of Korea’s collective fascination with personality classification stretch back decades. In the 1990s and early 2000s, blood type-based personality science—though later discredited—was all the rage, while the MBTI remains deeply entrenched in Korean youth culture, from classrooms to corporate offices and dating apps (The Korea Herald).
Why do these trends keep recurring? Experts say the answer lies in both social anxiety and the search for belonging. A 2025 nationwide survey by Embrain Trend Monitor found that 76% of Koreans in their twenties and 71.6% in their thirties “want to understand themselves accurately”, while an even greater portion—86% and 87.6%, respectively—admitted to being “curious about who they are”. Despite this, only about one-fifth to one-third felt they had actually succeeded in understanding themselves. Typology tests, then, fill an emotional gap, offering comfort, entertainment, and a sense of control.
Psychology experts, such as a professor from Dankook University’s Department of Psychology and Psychotherapy, have weighed in: “The trend reflects the MZ generation’s effort to understand themselves and build positive relationships with others.” A professor of psychology at Seoul National University sees “humans are wired to categorise and group things. Just like with MBTI or blood types, categorising people into teto men or egen men is another attempt to simplify complex human nature.” (straitstimes.com).
Still, these tests carry risks. Both experts caution that simplifying individuals through hormone analogies entrenches gender stereotypes and binary thinking. Classifications that start out as playful can become self-restrictive if taken too seriously, especially among highly competitive youth who look for predictors of success, romance, or social fit. “Blindly believing in these tests can lead to overgeneralisation and binary thinking. Identity tests should be treated lightly and used for reference only,” warns the Dankook University specialist.
The implications for Thailand are especially timely. In recent years, Thai youth have shown increasing interest in personality typing—MBTI groups on social media, blood type personality memes, and even the resurgence of astrology among Generation Z. These trends mirror South Korea’s, raising questions about whether Thailand will see a similar rise in hormone-inspired typology for dating and self-expression.
Thai psychologists would likely echo Korean concerns: while personality tests can help ease social anxiety and foster a sense of belonging, there is risk in letting such frameworks dictate self-concept or reinforce stereotypes. However, in a society where self-knowledge is becoming a vital social currency in the realms of romance, work, and social media, Thai youth may find novel value in exploring self-identity via such playful—but ultimately non-scientific—tools.
A look back at how “typing” the self has influenced Thai society shows a similar pattern. The popularity of blood type tests in Korea paralleled a craze for “birth year animal” personality quizzes in Thailand, and MBTI has already gained traction across campuses and workplaces. As yet, however, hormone-based frameworks have not broken into the Thai mainstream. Should the trend reach Thai shores, educators, parents, and youth leaders will need to help young people treat such tests critically—valuing introspection but recognising the limits of typology.
Looking forward, it is likely that the ceiling for personality tests will keep rising as long as young people face pressure to “know themselves” and “stand out” in competitive societies. Digital environments—often more impersonal and fast-paced than in-person communities—further fuel this appetite. What emerges, both in Korea and potentially in Thailand, is a social dynamic where playful forms of classification shape not only online identity, but also the texture of real-life relationships.
What should Thai readers take from Korea’s ‘teto-egen’ phenomenon? Importantly, treat all personality frameworks—including MBTI, blood types, and hormone archetypes—as tools, not truths. They may be fun, insightful, or useful for starting conversations, but self-understanding and relationship success depend on lived experience, openness, and a willingness to see oneself and others as more complex than any binary test can express.
For parents, educators, and youth mentors, now is the time to encourage media literacy and critical thinking around such trends. Introduce young people to evidence-based ways of self-discovery—like reflection, counselling, and open dialogue—and remind them that while online quizzes can spark connection, every individual’s value far exceeds any label.
For young Thais intrigued by these trends, remember: the search for self is lifelong and multifaceted. Take the tests, share your ‘type’, but also seek deeper connections and resist the temptation to let any quiz, however viral, limit your individuality.
Sources:
- ‘Teto’ or ’egen’? Young South Koreans turn to hormone-inspired identity tests (The Straits Times, 13 July 2025)
- The Korea Herald, 2025
- Expert commentary as reported in The Korea Herald and The Straits Times